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Thomas Gleixnerec8f24b2019-05-19 13:07:45 +01001# SPDX-License-Identifier: GPL-2.0-only
Joonsoo Kimeefa864b2014-12-12 16:55:46 -08002config PAGE_EXTENSION
3 bool "Extend memmap on extra space for more information on page"
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +09004 help
Joonsoo Kimeefa864b2014-12-12 16:55:46 -08005 Extend memmap on extra space for more information on page. This
6 could be used for debugging features that need to insert extra
7 field for every page. This extension enables us to save memory
8 by not allocating this extra memory according to boottime
9 configuration.
10
Akinobu Mitaee3b4292009-04-02 16:56:30 -070011config DEBUG_PAGEALLOC
12 bool "Debug page memory allocations"
Akinobu Mita7bc32f62011-03-22 16:32:46 -070013 depends on DEBUG_KERNEL
14 depends on !HIBERNATION || ARCH_SUPPORTS_DEBUG_PAGEALLOC && !PPC && !SPARC
Akinobu Mita7bc32f62011-03-22 16:32:46 -070015 select PAGE_POISONING if !ARCH_SUPPORTS_DEBUG_PAGEALLOC
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +090016 help
Akinobu Mitaee3b4292009-04-02 16:56:30 -070017 Unmap pages from the kernel linear mapping after free_pages().
Christian Borntraegerea6eabb2016-03-15 14:55:30 -070018 Depending on runtime enablement, this results in a small or large
19 slowdown, but helps to find certain types of memory corruption.
Akinobu Mitaee3b4292009-04-02 16:56:30 -070020
Vlastimil Babka4462b322019-07-11 20:55:09 -070021 Also, the state of page tracking structures is checked more often as
22 pages are being allocated and freed, as unexpected state changes
23 often happen for same reasons as memory corruption (e.g. double free,
Vlastimil Babka89745582019-09-23 15:34:42 -070024 use-after-free). The error reports for these checks can be augmented
25 with stack traces of last allocation and freeing of the page, when
26 PAGE_OWNER is also selected and enabled on boot.
Vlastimil Babka4462b322019-07-11 20:55:09 -070027
Akinobu Mita7bc32f62011-03-22 16:32:46 -070028 For architectures which don't enable ARCH_SUPPORTS_DEBUG_PAGEALLOC,
29 fill the pages with poison patterns after free_pages() and verify
Vlastimil Babka4462b322019-07-11 20:55:09 -070030 the patterns before alloc_pages(). Additionally, this option cannot
31 be enabled in combination with hibernation as that would result in
32 incorrect warnings of memory corruption after a resume because free
33 pages are not saved to the suspend image.
Akinobu Mita7bc32f62011-03-22 16:32:46 -070034
Christian Borntraegerea6eabb2016-03-15 14:55:30 -070035 By default this option will have a small overhead, e.g. by not
36 allowing the kernel mapping to be backed by large pages on some
37 architectures. Even bigger overhead comes when the debugging is
38 enabled by DEBUG_PAGEALLOC_ENABLE_DEFAULT or the debug_pagealloc
39 command line parameter.
40
41config DEBUG_PAGEALLOC_ENABLE_DEFAULT
42 bool "Enable debug page memory allocations by default?"
Christian Borntraegerea6eabb2016-03-15 14:55:30 -070043 depends on DEBUG_PAGEALLOC
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +090044 help
Christian Borntraegerea6eabb2016-03-15 14:55:30 -070045 Enable debug page memory allocations by default? This value
46 can be overridden by debug_pagealloc=off|on.
47
Vlastimil Babka0710d012022-05-25 13:25:59 +020048config DEBUG_SLAB
49 bool "Debug slab memory allocations"
50 depends on DEBUG_KERNEL && SLAB
51 help
52 Say Y here to have the kernel do limited verification on memory
53 allocation as well as poisoning memory on free to catch use of freed
54 memory. This can make kmalloc/kfree-intensive workloads much slower.
55
56config SLUB_DEBUG
57 default y
58 bool "Enable SLUB debugging support" if EXPERT
Vlastimil Babkae240e532022-11-14 18:13:45 +010059 depends on SLUB && SYSFS && !SLUB_TINY
Linus Torvalds8291eaa2022-05-27 11:40:49 -070060 select STACKDEPOT if STACKTRACE_SUPPORT
Vlastimil Babka0710d012022-05-25 13:25:59 +020061 help
62 SLUB has extensive debug support features. Disabling these can
63 result in significant savings in code size. This also disables
64 SLUB sysfs support. /sys/slab will not exist and there will be
65 no support for cache validation etc.
66
67config SLUB_DEBUG_ON
68 bool "SLUB debugging on by default"
69 depends on SLUB && SLUB_DEBUG
Linus Torvalds8291eaa2022-05-27 11:40:49 -070070 select STACKDEPOT_ALWAYS_INIT if STACKTRACE_SUPPORT
Vlastimil Babka0710d012022-05-25 13:25:59 +020071 default n
72 help
73 Boot with debugging on by default. SLUB boots by default with
74 the runtime debug capabilities switched off. Enabling this is
75 equivalent to specifying the "slub_debug" parameter on boot.
76 There is no support for more fine grained debug control like
77 possible with slub_debug=xxx. SLUB debugging may be switched
78 off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
79 "slub_debug=-".
80
Changbin Du8aa49762019-03-05 15:46:19 -080081config PAGE_OWNER
82 bool "Track page owner"
83 depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
84 select DEBUG_FS
85 select STACKTRACE
86 select STACKDEPOT
87 select PAGE_EXTENSION
88 help
89 This keeps track of what call chain is the owner of a page, may
90 help to find bare alloc_page(s) leaks. Even if you include this
91 feature on your build, it is disabled in default. You should pass
92 "page_owner=on" to boot parameter in order to enable it. Eats
SeongJae Park799fb82a2023-01-03 18:07:52 +000093 a fair amount of memory if enabled. See tools/mm/page_owner_sort.c
Changbin Du8aa49762019-03-05 15:46:19 -080094 for user-space helper.
95
96 If unsure, say N.
97
Pasha Tatashindf4e8172022-01-14 14:06:37 -080098config PAGE_TABLE_CHECK
99 bool "Check for invalid mappings in user page tables"
100 depends on ARCH_SUPPORTS_PAGE_TABLE_CHECK
101 select PAGE_EXTENSION
102 help
103 Check that anonymous page is not being mapped twice with read write
104 permissions. Check that anonymous and file pages are not being
105 erroneously shared. Since the checking is performed at the time
106 entries are added and removed to user page tables, leaking, corruption
107 and double mapping problems are detected synchronously.
108
109 If unsure say "n".
110
111config PAGE_TABLE_CHECK_ENFORCED
112 bool "Enforce the page table checking by default"
113 depends on PAGE_TABLE_CHECK
114 help
115 Always enable page table checking. By default the page table checking
116 is disabled, and can be optionally enabled via page_table_check=on
117 kernel parameter. This config enforces that page table check is always
118 enabled.
119
120 If unsure say "n".
121
Akinobu Mita6a11f752009-03-31 15:23:17 -0700122config PAGE_POISONING
Laura Abbott8823b1d2016-03-15 14:56:27 -0700123 bool "Poison pages after freeing"
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +0900124 help
Laura Abbott8823b1d2016-03-15 14:56:27 -0700125 Fill the pages with poison patterns after free_pages() and verify
126 the patterns before alloc_pages. The filling of the memory helps
127 reduce the risk of information leaks from freed data. This does
Kees Cook8c9a1342018-08-21 21:53:10 -0700128 have a potential performance impact if enabled with the
129 "page_poison=1" kernel boot option.
Laura Abbott8823b1d2016-03-15 14:56:27 -0700130
131 Note that "poison" here is not the same thing as the "HWPoison"
132 for CONFIG_MEMORY_FAILURE. This is software poisoning only.
133
Vlastimil Babka8f424752020-12-14 19:13:41 -0800134 If you are only interested in sanitization of freed pages without
135 checking the poison pattern on alloc, you can boot the kernel with
136 "init_on_free=1" instead of enabling this.
137
Laura Abbott8823b1d2016-03-15 14:56:27 -0700138 If unsure, say N
139
Joonsoo Kim95813b82016-03-17 14:19:29 -0700140config DEBUG_PAGE_REF
141 bool "Enable tracepoint to track down page reference manipulation"
142 depends on DEBUG_KERNEL
143 depends on TRACEPOINTS
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +0900144 help
Joonsoo Kim95813b82016-03-17 14:19:29 -0700145 This is a feature to add tracepoint for tracking down page reference
146 manipulation. This tracking is useful to diagnose functional failure
147 due to migration failures caused by page reference mismatches. Be
148 careful when enabling this feature because it adds about 30 KB to the
149 kernel code. However the runtime performance overhead is virtually
150 nil until the tracepoints are actually enabled.
Jinbum Park2959a5f2017-02-27 14:30:22 -0800151
152config DEBUG_RODATA_TEST
153 bool "Testcase for the marking rodata read-only"
154 depends on STRICT_KERNEL_RWX
Masahiro Yamadaa7f7f622020-06-14 01:50:22 +0900155 help
Jinbum Park2959a5f2017-02-27 14:30:22 -0800156 This option enables a testcase for the setting rodata read-only.
Steven Price30d621f2020-02-03 17:36:20 -0800157
Zong Li375d3152020-06-03 16:03:52 -0700158config ARCH_HAS_DEBUG_WX
159 bool
160
161config DEBUG_WX
162 bool "Warn on W+X mappings at boot"
163 depends on ARCH_HAS_DEBUG_WX
164 depends on MMU
165 select PTDUMP_CORE
166 help
167 Generate a warning if any W+X mappings are found at boot.
168
169 This is useful for discovering cases where the kernel is leaving W+X
170 mappings after applying NX, as such mappings are a security risk.
171
172 Look for a message in dmesg output like this:
173
174 <arch>/mm: Checked W+X mappings: passed, no W+X pages found.
175
176 or like this, if the check failed:
177
178 <arch>/mm: Checked W+X mappings: failed, <N> W+X pages found.
179
180 Note that even if the check fails, your kernel is possibly
181 still fine, as W+X mappings are not a security hole in
182 themselves, what they do is that they make the exploitation
183 of other unfixed kernel bugs easier.
184
185 There is no runtime or memory usage effect of this option
186 once the kernel has booted up - it's a one time check.
187
188 If in doubt, say "Y".
189
Steven Price30d621f2020-02-03 17:36:20 -0800190config GENERIC_PTDUMP
191 bool
192
193config PTDUMP_CORE
194 bool
195
196config PTDUMP_DEBUGFS
197 bool "Export kernel pagetable layout to userspace via debugfs"
198 depends on DEBUG_KERNEL
199 depends on DEBUG_FS
200 depends on GENERIC_PTDUMP
201 select PTDUMP_CORE
202 help
203 Say Y here if you want to show the kernel pagetable layout in a
204 debugfs file. This information is only useful for kernel developers
205 who are working in architecture specific areas of the kernel.
206 It is probably not a good idea to enable this feature in a production
207 kernel.
208
209 If in doubt, say N.
Zhaoyang Huangb2db9ef2023-01-19 09:22:24 +0800210
211config HAVE_DEBUG_KMEMLEAK
212 bool
213
214config DEBUG_KMEMLEAK
215 bool "Kernel memory leak detector"
216 depends on DEBUG_KERNEL && HAVE_DEBUG_KMEMLEAK
217 select DEBUG_FS
218 select STACKTRACE if STACKTRACE_SUPPORT
219 select KALLSYMS
220 select CRC32
221 select STACKDEPOT
222 select STACKDEPOT_ALWAYS_INIT if !DEBUG_KMEMLEAK_DEFAULT_OFF
223 help
224 Say Y here if you want to enable the memory leak
225 detector. The memory allocation/freeing is traced in a way
226 similar to the Boehm's conservative garbage collector, the
227 difference being that the orphan objects are not freed but
228 only shown in /sys/kernel/debug/kmemleak. Enabling this
229 feature will introduce an overhead to memory
230 allocations. See Documentation/dev-tools/kmemleak.rst for more
231 details.
232
233 Enabling DEBUG_SLAB or SLUB_DEBUG may increase the chances
234 of finding leaks due to the slab objects poisoning.
235
236 In order to access the kmemleak file, debugfs needs to be
237 mounted (usually at /sys/kernel/debug).
238
239config DEBUG_KMEMLEAK_MEM_POOL_SIZE
240 int "Kmemleak memory pool size"
241 depends on DEBUG_KMEMLEAK
242 range 200 1000000
243 default 16000
244 help
245 Kmemleak must track all the memory allocations to avoid
246 reporting false positives. Since memory may be allocated or
247 freed before kmemleak is fully initialised, use a static pool
248 of metadata objects to track such callbacks. After kmemleak is
249 fully initialised, this memory pool acts as an emergency one
250 if slab allocations fail.
251
252config DEBUG_KMEMLEAK_TEST
253 tristate "Simple test for the kernel memory leak detector"
254 depends on DEBUG_KMEMLEAK && m
255 help
256 This option enables a module that explicitly leaks memory.
257
258 If unsure, say N.
259
260config DEBUG_KMEMLEAK_DEFAULT_OFF
261 bool "Default kmemleak to off"
262 depends on DEBUG_KMEMLEAK
263 help
264 Say Y here to disable kmemleak by default. It can then be enabled
265 on the command line via kmemleak=on.
266
267config DEBUG_KMEMLEAK_AUTO_SCAN
268 bool "Enable kmemleak auto scan thread on boot up"
269 default y
270 depends on DEBUG_KMEMLEAK
271 help
272 Depending on the cpu, kmemleak scan may be cpu intensive and can
273 stall user tasks at times. This option enables/disables automatic
274 kmemleak scan at boot up.
275
276 Say N here to disable kmemleak auto scan thread to stop automatic
277 scanning. Disabling this option disables automatic reporting of
278 memory leaks.
279
280 If unsure, say Y.
281